Seaming apparatus



Filed Feb. 7, 1955 2 Sheets-Sheet l FIGI.

Nov. 24, 1959 L. COAKLEY 2,914,108

SEAMING APPARATUS Filed Feb. 7, 1955 2 Sheets-Sheet 2 i l'l i l a s l 45 49 65 55 WEI),

United Stat6S P e SEAMIN G APPARATUS Lige Coakley, Pepperell, Mass., a ssignor to Bemis Bro Bag Company, St. Louis, Mo., a corporation of Missoun This'invention relates to apparatus for longitudinally seaming web material, more particularly to apparatus for forming the longitudinal seams of paper bag tubing.

Among the several objects of the invention may be noted the provision of apparatus for longitudinally seaming web material, more particularly for forming the longitudinal seams of paper bag tubing, by means of a thermoplastic adhesive material; the provision of apparatus of this class whereinthe 'Web material is continuously fed through the apparatus at one speed or another, and wherein the rate of application of the adhesive to the web material is automatically controlled in accordance with the speed of the web material; and the provision of apparatus of this class which is of economical construction and reliable in operation. Other objects and features will be in part apparent and in part pointed out hereinafter. v l

The invention accordingly comprises the constructions Patented Nov. 24, 1959 corresponding to the lateral spacing of the scams 7 and 9. The thermoplastic material used is of such character as to bond the margins of the plies" together upon-cooling and solidifying. Polyethylene has been 'foundvery suitable for this purpose, particularly for bonding kraft paper. Asphalt has also been used.

The two stripesof melted thermoplastic material required for forming the two seams 7 and are applied to the paper by meanscomprising an applicator head 23, a melting pot 25 for containinga supply of the melted thermoplastic material, and a pump ,27for pumping the melted material from the pot to theapplicator head. Electrical immersion heaters for melting thermoplastic material in the pot are indicated at 29. Electrical eonnectors for making electrical connections to the heaters are indicated 'atf3 i The pump *27 is of a type the output of which is prov portional to its speed, for example, 'a gear pump. It is hereinafter described, the .:scope .of the invention being indicated in the following claims.

In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated,

Fig. 1 isa plan view of an apparatus of this-invention;

Fig. 2 .is an enlarged'transverse vertical section taken on line '22 of Fig. l; i

Fig. 3 is a plan view of amelting-pot and applicator head assembly per'se; a

Fig. 4 is a frontelevation' of the Fig. 3 assembly;

Fig. 5 is a vertical section taken on line 5-5 ofFig. 4;

Fig. 6 is a horizontal section taken on line 6-6 of Fig. 4; and,

Fig. 7 is a horizontal section taken on line 7--7 of Fig. 4.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Referring to the drawings, an apparatus of this invention is shown in conjunction with a tuber for forming a continuous web of paper W into tubing T which is ultimately segmented into individual bag tubes. The tuber is of conventional character. The bed of the tuber is indicated at 1 in Figs. 1 and 2. The paper web W is shown in Figs. 1 and 2 as a two-ply paper web, the plies being designated 3 and 5. These plies are laterally offset with respect to one another, as is conventional in the manufacture of bag tubing, so that the longitudinal ply scams 7 and 9 of the tubing T are laterally offset with respect to one another. Feed rolls for feeding the tubing T (and the web W) are indicated at 11, 13, 15 and 17. These are positively driven through a drive generally designated 19 from a variable speed drive unit 21.

Each seam 7 and 9 is formed by applying a stripe of melted thermoplastic material P to the paper, the stripes being located to come between the overlapping margins of the respective plies 3 and 5, and by pressing together the overlapping margins with the bonding material therebetween. This pressing is effected by means of the feed rolls 13 and 15, which are laterally spaced at distance located in the melting pot to be submerged in the melted thermoplastic material contained in the pot, being mounted on a base 33 fixed to the bottom of the pot. The base 33 has a horizontal intake passage -35'leadin'g to a vertical passage 37 in communication with the inlet of the pump. The output of the pump is delivered to two vertical passages 39 and 41 in the base 33. Fastened to the underside of the bottom of the melting pot is a block 43 which has vertical passages 45 and 47 in line with passages 39 and 41 and'ho'rizontal passages 49 land 51 leading from the passages 45 and 47. The bottom of the meltingpotlhas openings aligned with 39 45 and 41, 47.

The block 43 has a bottom notch 53 receiving an electrical strip heater 5 5. This strip heater projects out from under the melting pot and carries the applicator head 23 at its outer end. The head 23 has passages 57 and 59 leading to delivery nozzles 61 and 63 which are located to apply the stripes of the thermoplastic material-in the proper spaced relation. Metal tubes 65 :and 67 lead from the passages 49 and 51 above the stripgh'e'ater 55 to the passages 57 and 59 in the head. The head is additionally supported bya rod 69 which extends fromthe block 43.

On the top of the melting pot" is, aplatform 71carrying a speed-reducing gear 'box 73." Theoutput shaft 6f the gear box is connected to drive the pump shaft 77 via an angle gear box 79. A flexible shaft 81 connects the variable-speed drive unit 21 and the input shaft 83 of the gear box 73.

In the operation of the apparatus, the pump 27 is continuously driven in timed relation to the speed of the web W. Since the means for feeding the web W (feed rolls 11, 13, 15 and 17) and the pump 27 are both driven from the variable speed drive unit 21, the web feeding means and the pump are interconnected so that the ratio of the speed of the pump and the speed of the web feeding means is maintained substantially constant even though the web speed is changed by adjusting unit 21. The output of the pump is delivered to the head 23 and extruded downward through the nozzles 61 and 63 onto the paper to provide the two stripes of the melted thermoplastic material on the paper. Bulk thermoplastic material is melted in the pot 25 by the immersion heaters 29, and maintained in its melted condition from the melting pot to the head by the heat generated by the strip heater 55. If the speed of the paper is changed, the rate of application of the melted thermoplastic is inherently changed in proportion so that the proper amount of thermoplastic material is applied to the paper for forming the seams.

It will be understood that the principles of the invention are applicable to forming only one seam, or more than two seams, simply by using an applicator head with one nozzle or more than two nozzles.

In view of the above, it will be seen that the several objects of the inventionare achieved and other advan-.

tageous results attained. 7

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown inthe accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

1. Apparatus for longitudinally seaming continuous web material comprising means for continuously feeding the web material, and means for continuously applying a stripe ofa thermoplastic material to the web material, said thermoplastic applying means comprising a head for delivering melted thermoplastic material onto the web material, a receptacle for a supply of melted thermoplastic material, a pump for continuously pumping the melted thermoplastic material from the receptacle to the head, the

output of the pump being generally proportionalto the pump speed, and means for continuously driving the pump interconnected with said means for feeding the web material for maintainingthe ratio'of the speed of the pump and the speed of said feeding meanssubstantially constant, whereby upon a change in the speed of web-feed, the rate of application of the thermoplastic material is proportionately changed.

2. Apparatus for longitudinally seaming continuous web material comprising means for continuously feeding the web material, and means for continuously applying a stripe of a thermoplastic material to the web material said thermoplastic applying means comprising a head for delivering melted thermoplastic material onto the web material, a melting pot for thermoplastic material, a pump in the melting pot for continuously pumping melted thermoplastic material from the pot to the head, the output of the pump being generally proportional to the pump speed, and means for continuously driving the pump interconnected with said means for feeding the web material for maintaining the ratio of the speed of the pump and the speed of said feeding. means substantially constant, whereby upon a change in the speed of web feed, the rate of application of the thermoplastic material is proportionately changed.

3. Apparatus for longitudinally seaming continuous web material comprising means for continuously feeding the web material, and means for continuously applying a stripe of a thermoplastic material to the web material, said thermoplastic applying means comprising a head for delivering melted thermoplastic material onto the web material, a melting pot for thermoplastic material, a pump in the melting pot, a tube leading from the pump to the head, said pump being adapted continuously to deliver melted thermoplastic material from the pot through the tube to the head, the output of the pump being generally proportional to the pump speed, means for continuously driving the pump interconnected with said means for feeding the web material for maintaining the ratio of the speed of the pump and the speed of said feeding means substantially constant, whereby upon a change in the speed of web feed, the rate of application of the thermoplastic material is proportionately changed, and means for heating the tube and head.

4. Apparatus for longitudinally seaming web material comprising means for continuously feeding the web material, and means for applying a plurality of stripes of thermoplastic material to the web material, said thermoplastic applying means comprising a melting pot for thermoplastic material, a pump in the melting pot, the output of the pump being generally proportional to the pump speed, means for continuously driving the pump interconnected with said means for feeding the web material for maintaining the ratiolof the speed of the pump and the speed of said feeding means substantially constant, whereby upon a change in the speedof web feed, the rate of application of the thermoplastic material is proportionately changed, a strip. heater having one end under the bottom of the pot and projecting out from under the pot, a head having a plurality of delivery nozzles for the melted thermoplastic material mounted on the outer end of the strip heater, and tubes through which melted thermoplastic material is adapted to flow from the pump to the nozzles, said tubes extending over the strip heater.

References Cited in the fileof this patent UNITED STATES PATENTS 345,236

Jordan July 6, 1886 1,152,922 Sherrer Sept. 7, 1915 2,206,965 Lakso July 9, 1940 2,283,155 Lang May 12, 1942 2,466,735, Piazze Apr. 12, 1949 2,519,102 Bergstein Aug. 15, 1950 2,598,852 Staege June 3, 1952 2,718,915

Piazze Sept. 27, 1955 

